Electromagnetism Definition and 853 Threads

I've just finished my first term in an undergrad electromagnetism course using Wangsness as a textbook and we ended on the displacement field. I feel like Wangsness doesn't give a very good explanation of what the whole point of it actually is, and I still don't quite understand how to use it...

Homework Statement An infinite wire of linear charge density \lambda lies on the z axis. An insulating cylindrical shell of radius R is concentric with the wire and can rotate freely about the z axis. The charge per unit area on the cylinder is \sigma = -\lambda/2\pi R while the mass per unit...

electromagnetism -- interaction between the electron and the quarks Which theory explains the electromagnetic interaction between the electron and the quarks within a hydrogen atom ? Is it QED or should I look at Standard Model ?

In electromagnetism we introduce the following differential form \begin{array}{c} \mathbb{F}=F_{\mu \nu}dx^{\mu}\wedge dx^{\nu} \end{array} Then the homogeneus Maxwell equations are equivalent to: \begin{array}{c} d\mathbb{F} = 0 \end{array} And is nice, but what purpose does this have...

I have recently come across relativistic electromagnetism so I am very new to it. The situation described to me was one where a positive test charge moves above a wire with a velocity V which matches the current in the wire in both magnitude and direction. Apparently, from the test charge's...

Homework Statement Here's an image of the circuit : http://gyazo.com/b313887dea7780e1226fcc8d4796a63d 1. Explain two ways to make the bulb glow without changing the circuit. 2. Explain why an AC generator replacing the battery could also make the bulb glow. Homework Equations The Attempt at...

Imagine a set of train tracks. Now there is one bridge (a resistor) connecting the two rails in one spot. On a different spot, there is rolling axle that acts as another bridge and it makes good electrical connection with the rails creating a full rectangular circuit. This axle rolls at a...

The question I'm wanting to ask is, Why does light travel through a vacuum? This is too big of a question to start with, though. Before making this thread, I read around and tried to make a starter question.If I'm not confused by the information I've found, a fundamental reason of why light can...

Hello, I am an EE at college, and I will be graduating in (most likely) 3 semesters. Out of all of the parts of EE, I have really enjoyed electromagnetism the most and I was wondering if anyone had any insight into careers that revolve around EM. I just don't have a good grasp of what...

In basic but precise terms, can someone please explain to me the fundamentals on how/why these things operate? I've been reading about how these things work but I really want a good understanding on why these works too. Thanks :)

Natural Magnets: How do they work? I'd prefer a technical answer on a subatomic level. Electromagnets: Say you have a copper wire hooked up to a negative terminal and on the other end of the wire a positive terminal. Due to a potential difference, electrons flow from the negative to the...

Hi everyone, In one of the assignments in a course on classical field theory I'm given the action S = \int d^4 x \mathcal{L} where \mathcal{L} = -\frac{1}{16\pi} F_{\mu \nu} F^{\mu \nu} - A_{\mu}j^{\mu}. I'm now supposed to construct the canonical momenta \pi_\mu = \frac{\delta...

1. A 0.034 kg copper rod is hung by two wires and placed in a constant magnetic field. A current of 14 A runs through the 0.050 m long copper rod, making it hang at an angle of 34° from the vertical as attached in the diagram. What is the magnetic field strength holding the copper rod in...

1. The diagram attached shows a 0.010 kg metal rod resting on two long horizontal frictionless rails which remain 0.40 m apart. The circuit has a resistance of 3.0 W and is located in a uniform 0.20 T magnetic field. Find the initial acceleration and maximum velocity for the rod. a) Initial...

1. A coil of 25 turns of wire is suspended by a thread. When a current flows through the coil, the tension in the thread is reduced by 4.0 x 10-2 N. What are the magnitude and direction of the current? {magnitude of current; direction of current} a) 4.1 A; clockwise b) 0.16 A; clockwise c)...

1. Four conductors of equal length are each moved through a uniform magnetic field moving away from us (into the page) in different directions and with different speeds, as shown in my attached diagram. While the four conductors are being moved through the field, in which conductor will the...

1. A 35 loop square coil 0.12 m on a side is positioned in a 0.050 T magnetic field. A 0.20 kg mass is suspended from one side of the coil as shown in the diagram attached. How much current must pass through the coil in order for the coil to remain horizontal? A. 2.3 A B. 4.7 A C. 9.3 A D. 330...

The circle is the fiber over Minkowski spacetime for electromagnetism? I want to make connection to the classical vector potential via some " picture" involving this circle. Does the following come close? Can I consider a 3 dimensional surface in C_1XMinkowski space that at a given slice of...

I'm taking a first year physics course and have been having a little trouble with the basics of Newtons laws and forces and whatnot, though nothing that can't be fixed with a bit more hard work. I'm looking ahead now and seeing a lot of EM material, and after kind of taking a brief look at...

I realize atoms are held together by STRONG electromagnetism, but if you were to convert this energy into an everyday scenario, how strong would it really be? I'm trying to explain the power behind a small atom and I feel using a 'real', known object. Thank you in advance for any answers.

My last thread for a while. Could possibly be a dumb question so you must forgive I am not well versed in these matters but have become curious about physics in general. I was just wondering if it was possible that electromagnetism and gravity are actually connected?

Homework Statement A large block of dielectric contains small cavities of various shapes whose sizes are much smaller than the block. The dielectric has uniform polarization P except those cavities which are assumed not to disturb the polarization of dielectric. (a) Show that, inside a...

Are there any textbooks on something like this, a self consistent treatment of classical electromagnetism (relavistic is fine too) where the field equations are solved alongside with the matter fields.

I'm currently taking first year Electromagnetism and I'm studying for the final, I was wondering if anyone has links to some good resources to help? Currently I'm just rewriting my notes and marking down any concepts I need to look into.

Homework Statement #45 What is the magnitude and the direction of the current? Homework Equations The Attempt at a Solution I know how to get the magnitude but i don't get the current direction...how do i find out which way the current goes? What is the general rule to find the direction of...

I have come back to studying physics after 5 years and I'm doing a course in electromagnetism. I've come to the wave equation and I'm a little rusty. For example, the general solution, A(z,t) = Acos(2*pi*z/L - 2*pi*f*t + phi) I know basically what the terms mean, but I'm unsure how they...

Hey guys, it's been a long time since I've taken physics and I was hoping for some help on this theoretical situation. Ok, let's say you have a positively charged ball placed in the middle of a negatively charged circle. Outside of the circle are 4 positively charged balls, one to the north...

Cyclosis in Maxwell's "Electromagnetism (Vol.1)" On page 16, sec. 18 of his "Treatise on Electricity and Magnetism (Vol. 1)", Maxwell introduces the terms cyclosis and cyclomatic number. I cannot visualize the geometry that he describes and so the next few pages are lost on me. Please help me...

I know I'm an electrical engineering major but I'm looking to get the most out of my courses. I'm curious about the significant differences between the two intro to electromagnetism courses offered at my school: the "engineering" and the "physics" versions. I'm not sure I get the whole applied...

Here is a homework question that I have for my general physics class; our professor ran out of time during lecture and did not get to explain the material very well so I am a little lost. A 47.0 g ball of copper has a net charge of 1.7 µC. What fraction of the copper's electrons have been...

Author: Gerald L. Pollack and Daniel R. Stump Title: Electromagnetism Amazon Link: https://www.amazon.com/dp/0805385673/?tag=pfamazon01-20 Prerequisities: Calculus-based intro physics and a year of calculus Contents History and Perspective Vector Calculus Basic Principles of...

Author: Jerrold Franklin Name: Classical Electromagnetism Amazon url: https://www.amazon.com/dp/0805387331/?tag=pfamazon01-20 Level: First year graduate course text. User comments: Meir Achuz This book is on the level of Jackson, but with the readability of Griffiths. It has...

Usually I like to expand my questions (no matter how dumb they may be) with proof/ history/ statements/ comments, but this time... I'm going to be a little more straight to the point. Btw, if you notice me say something incorrect, please tell me; the things I am stating here are said in the way...

We are usually told in an introduction to general relativity that when special relativity was completed, there was a contradiction with Newtonian physics. The Newtonian gravitational force of M on m is F_g = -G \frac{M m}{r^2} \hat{r} where \vec{r} is the spatial vector from M to m. This...

Homework Statement Derive Tμν=FμλFνλ-1/4ημνFλθFλθ From \mathcal{L}=1/4F_{μν}F^{μν}+A_μJ^μ Homework Equations Above 3. The Attempt at a Solution The first term of the given equation and the second term of the equation to prove are i believe the same.i know, Jμ=\partial_νF^{μν}...

From a historical point of view, I don't see how people like Newton were studying the solar system and the effects of gravity on the moon before figuring out the electromagnetic phenomenon. It seems like it would be much harder to study the orbits of the planets than electricity, since at least...

Hello! I' currently reading EM and am in need of a verification that I understood it correctly before proceeding. Just to see if I got this right: The energy flowing out of a point, p, is described by the Poynting vector of the field at that point. The momentum density of the field is...

Homework Statement A sample of thorium-226 is stored in a lead box. Thorium-226 undergoes alpha decay. The lead box has a small opening on the left side to allow a stream of alpha particles to escape. In the sample a nucleus of thorium-226 is at rest when it undergoes alpha decay. The daughter...

Early next year I will be beginning an Electromagnetism unit. However, I think I should refresh my maths over the summer break first. Here is the Unit Description from the uni website: A detailed treatment of electric and magnetic fields and theory sources leading to the formulation of...

I was wondering about some basic concepts of electromagnetism. Firstly, resistance is kind of like the measure of obstruction in a conducting material; right? So maybe the atomic properties of the conducting material are such that the current of electrons gets obstructed and ends up colliding...

Homework Statement Given a sphere of radius R with a volumic charge distribution p find the function p. The electric field inside of the sphere is radial with a constant modulus E Homework Equations div E = p / ε ∫∫E.ds = 1/ε * ∫∫∫ p * dV The Attempt at a Solution I tried to solve it...

Homework Statement 1. http://http://tinypic.com/r/2r386q1/6 Determine the polarity of the induced magnetic field and direction of electron flow for each. Indicate which end of the generator becomes a negative terminal. I don't know how to do the last two that you see e and f 2. In the...

Homework Statement A solenoid lies horizontally with a current balance WXYZ balanced in the solenoid core. Sides WX and ZY are 7.1 cm and side XY is 1.9cm. A current of 6.0A flows through the conductor of the balance. If a 17.6g mass is necessary to balance the current balance what is the...

Hi, studying for exam and checking if i am doing this question correctly , Q: Cylinder radius R=1m length L=2m exists in free space with no other charges nearby. Cylinder volume is charged with uniform charge Q= 7C. (a)Find the charge density in Coulombs per cubic metre. (b) charge...

I have a choice between 2 classes next semester that conflict, and if I choose one I will graduate without taking the other. Partial differential equations or electromagnetism? I'm a math/chemistry major and I want to go to grad school for chemical physics or physical chemistry. Any insight as...

Homework Statement that fig is taken from the book of The Feynman Lectures on Physics. The fig above shows that if the copper disc is rotated (by a hand), there will be induced current, measured by the galvanometer. this engineering principle is the basic principle of a generator. what would...

Homework Statement A dielectric slab with a susceptibility ##\chi_e## rests on a conducting plate whose upper surface carries a free surface charge density ##\sigma##. Show that the polarization surface charge density ##\sigma_{pol}## on the lower face of the dialectic slab is: ##\sigma_{pol}...

I am currently reading a book about the electromegnetism. When I went through the introductory chapter, there is a small part that I do not understand clearly. Therefore, I hope that I can seek help here. Quote: --- --- --- --- ---...

Hi This might seem odd but I need to explain my friend on this Friend and I agreed that Classical physics is time reversible (i.e. laws remain same if time is reversed.. e.g. gravitational pull on a projectile.) only exception is II law of Thermodynamics (which talks of irreversible decrease...

Homework Statement When we have an iron core in a solenoid, the iron core will become magnetised. But if I were to put a piece of iron in front of the iron and solenoid the piece of iron will come out like in a door chime. But as it comes out, will the magnetic field be stretched and elongated...